What is the mechanism of action presumed for most antidepressants?

Most antidepressants are believed to primarily work by increasing the levels of certain neurotransmitters, particularly serotonin and norepinephrine, in the brain. This mechanism of action is fundamental to the pharmacodynamics of commonly prescribed classes of antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and norepinephrine-dopamine reuptake inhibitors (NDRIs).

SSRIs, for example, focus specifically on blocking the reuptake of serotonin into the presynaptic neuron, thereby increasing its availability in the synaptic cleft. This enhancement of serotonin signaling is associated with improvements in mood and emotional regulation. Similarly, certain classes of antidepressants, such as serotonin-norepinephrine reuptake inhibitors (SNRIs), target both serotonin and norepinephrine, further emphasizing the importance of these neurotransmitters in the treatment of depressive symptoms.

In clinical practice, the modulation of serotonin and norepinephrine is key, as deficiencies or imbalances in these neurotransmitter systems have been linked to depressive disorders. Hence, by increasing the availability of these neurotransmitters, antidepressants can help alleviate the symptoms of depression. Understanding this mechanism is crucial when considering treatment options for individuals suffering from mood disorders.